The NB rat is a black-hooded inbred strain particularly susceptible to induction of prostate adenocarcinoma by implantation of sex hormones in young male rats. Such hormonally induced prostate tumors can be readily transplanted in NB, but not other strains of rats. Further, the natural history and histopathology of NB rat prostatic tumors are similar to human prostate neoplasia. Hitherto, the NB rat has been primarily used as a model for studying both the interactions of hormones and prostate cancer and for testing chemotherapeutic agents. In contrast to these therapeutic studies, observations from this laboratory have demonstrated the presence, 14 to 28 days following syngeneic transplantation of prostate tumors, of an IgG antibody which reacts specifically with NB rat prostate tumor, but not normal prostate, liver, or leukocytes. The specificity of this reaction resides in the F(ab2) portion of IgG from tumor bearing, but not control, NB rats. Futhermore, the serum reacts with both serially passaged and first generation tumors. We believe, therefore, that the NB rat prostate adenocarcinoma model will permit development and characterization of tumor specific antibodies/antigens. To develop this, and to avoid the use of heteroantisera, we propose to fuse tumor bearing (and normal) NB rat spleen with the non-secreting mouse myeloma SP2/0-Ag 14. Such hybridomas will be serially cloned and the supernatants assayed for activity against prostate tumors by use of a rapid enzyme-linked immunoassay. The specificity of the monospecific antibody generated will be studied by comparing its reactivity with NB prostate tumors, normal adult and fetal tissues, and rat sera proteins. It is hoped that these monospecific antisera will then be applied, in future years of study, in immunodiagnosis, biochemical characterization of tumor antigens, and immunotherapy.